Art of forming bag bottoms



Jan. 21, 1958 K. A. RUSCH 2,820,497

ART oF FORMING BAG BoTToMs Filed April 25, 195e ,4 frog/Vans.

it l? ART F FRMHNG BAG BOTTOMS Kenneth A. Rusch, Milwaukee, Wis.,assigner to Milprint, inc., lviiiwauiree, Wis., a corporation ofDelaware The present invention relates generally to improvements in theart of packaging, and relates more particularly to the provision `of animproved commodity bag and' the method of producing the same.

A primary object of the invention is to providey an` improved commodityreceiving bag which is strong and durable in construction and has anexceedingly strong and effective leak-proof bottom seal and which maymoreover `be readily produced in quantity and at low cost in accordancewith a novel method.

It has heretofore been co-mmon practice to commercially producecommodity bags from webs of heat scalable ribbon/stock by first foldingthe advancing web into fiat tubular formation, then longitudinally heatsealing overlapped edge portions to complete the* tube, thereaftersevering the tube into sections of desired l`ength and by subsequentlyeither sealing the Walls directly to each other transversely across anend of the successive sections by application of heat and pressure or byfolding an end ofl each section back upon itself and finally applyingheat and pressure tothe four thicknesses of the folded over portion tothereby heat seal the. endv of each tube section and provide the bag.While these, prior heat 'sealing methods and the bags produced therebyhave proven quite satisfactory as applied to packaging materials o'fcertain types capable of being readily heat sealed While withstandingrelatively high temperatures for sufficient periods of time to permitfirm bonding and strong seals, many films which possess highly desirablecharacteristics for packaging purposes have an extremely critical rangein which heat may be applied safely and Without resultant damage 'to thematerial, and these films therefore cannot all be readily adapted foruse as commodity bags in accordance with prior production methods ofheat sealing.

It is therefore a more specific object of the present invention toprovide an improved commodity bag structure and method of producing thesame which obvia-te the objections and disadvantages attendant priorknown structuresand production methods.

Another specific object of this invention isl to provide :t commoditybag formed of heat sealable material and. having a novel and improvedhighly efficient leak-proof and sift-proof bottom seal formed with theaid of heat andpressure.

Another specic object of my invention is to provide an improved methodof commercially producing commodity bags and of effecting the bottom ortransverse end seals therein by a relatively simple and unique heatsealing operation.

Still another specific object of my present invention is to provide animproved commodity bag comprising, a` flat tubular body, one end of thebody being folded back upon one of the side walls thereof and beingsecured to the adjacent side wall by a heat seal extending transverselythereacross, and the folded end portion beyond theheatseal being free ofattachment to the adjacent side wall with both thicknesses of they freeportion thereof being secured to each other.

2,82@,497 Patented Jan. 2l, 1958 An additional specific object of thepresent invention is to provide an improved method of producingcommodity bags, which comprises, forming a fiat tubular body from asheetof heat scalable material, transversely folding an end of the body backupon one of its side walls, sealing the folded portion adjacent the foldline through both thicknesses thereof to the adjacent body side wall byapplication of heat and pressure, and securing both thicknesses of thefree end of the folded portion beyond the seal to each other byapplication of heat and pressure only to the folded portion.

These and other specific objects and advantages of the invention willbecome apparent from the following detailed description.

A clear conception of the features constituting the present inventionand of the several steps of the improved method of producing a typicalcommodity bag in accordance therewith may be had by referring to thedraw ing accompanying and forming a part of this specification whereinlike reference characters designate the same or similar parts in thevarious views.

Fig; l is a fragmentary side view diagrammatically illustrating typicalapparatus for facilitating production of commodity bags in accordancewith the improved method and showing a flat tube of suitable packagingmaterial being transversely severed;

Fig. 2 is another fragmentary diagrammatic side view just prior to thetransverse folding operation;

Fig. 3 is a similar fragmentary diagrammatic side View showing the startof the folding operation;

Fig. 4 is still another fragmentary side view showing the end of thetube folded back over the upper guide plate;

Fig. 5 is a fragmentary diagrammatic side view just prior to the heatsealing operation;

Fig. 6 is a similar view with the folding plate withdrawn and showingthe tube being transversely heat sealed to form the bag bottom;

Fig. 7 is an enlarged fragmentary perspective view illustrating the samestep as shown in Fig. 5 in which the end of the tube is folded and isabout to be transversely sealed; and

Fig. 8 is a similarly enlarged perspective view of a typical flatcommodity bag produced in accordance with thc improved method andembodying the improved bottom construction.

While the invention has been particularly shown and described herein asbeing especially advantageously applicable in the production of plainsquare cut commodity bags formed of thin heat scalable films which arehighly sensitive to heat and require great care in the control of theheat during sealing operations, it is not desired or intended to therebyunnecessarily restrict or limit the invention since the improvements mayalso be utilized to good advantage in the production of gusset type bagsformed of any heat scalable materials. It is furthermore contemplatedthat certain specific descriptive terms used herein shall be given thebroadest possible interpretation consistent with the disclosure.

In accordance with my present improved method of producing commoditybags having the novel and improved bottom construction, I initially folda continuous ribbon or web of thin iiexible heat scalable film materialalong spaced longitudinal lines and seal the overlapping longitudinaledges thereof in a customary manner to form a flat tubular body whichmay be severed into desired lengths. Next, an end portion of the tubularbody is folded back upon one of its side walls along a transverse foldline, and the body side walls are internally separated adjacent to thefold line while the folded portion remote from the fold line isseparated from the adjacent body side wall. Then, sealing heat andpressure isl applied transversely across the folded portion adjacent tothe fold line and in the area in which the side walls are internallyseparated to thereby secure both thicknesses of the folded portion toeach other and to the adjacent side Wall only, and sealing heat andpressure is likewise applied transversely across the folded portionremote from the fold line and in the area in which the folded portion isseparated from the adjacent side wall to thereby secure both thicknesesof the free end of the folded portion only to each ot er.

In the commercial exploitation of the improved bag producing method, theat tubular body 10 and longitudinal side seam 11 thereof may be formedwith the aid of commercially available apparatus and in a well knownmanner requiring no further description, and the tube may betransversely severed into desired lengths with the aid of suitablecooperating knives 12, 13 as shown in Fig. 1. To maintain the side Walls1d, 15 of the tubular body 10 internally separated, the tube is advancedabout a separating and backing plate or internal former 16 and directlybeneath an external separating and backing plate 17 which also serves asa guide plate during the transverse folding operation, the plate 17being reciprocable from a position shown in Figs. 2 to 4 inclusivewherein the forward edge thereof is in approximate alineinent with theforward edge of the former 16 to a position such as shown in Figs. 5 and6 in which the plate 17 is retracted to a position somewhat rearwardlyof the forward edge of the former 16. For folding the end portion 18 ofthe tube 15B back upon the side wall 14, a suitable folding plate 19 maybe provided which is vertically and laterally movable, as shown in Figs.2 to 5, to fold the portion 18 about the edges of the cooperating plates16, 17 to a position above the side wall 14, whereupon the folding plate19 may be withdrawn and the plate 17 may be retracted as described to aposition between the folded portion 18 remote from the fold line 2t? andthe side wall 14 of the tube. The final sealing operation may then beperformed with the aid of a heat sealing bar 21 having laterally spacedlegs 22, Z3 extending transversely across the tube, the bar 21 beingvertically movable into contact with the folded portion 18 of the tube,as shown in Figs. 5 and 6, with the leg 22, thereof cooperating with abacking pad 24 on the internal separating plate 16 to apply sealing heatand pressure transversely across the portion 1d adjacent to the foldline 2li and the leg 23 thereof cooperating with a backing pad 25 on theseparating plate 17 to apply sealing heat and pressure transverselyacross the portion 1S remote from the fold line 2li.

The commodity bag thus formed comprises, in general, a flat tubular body1t) having an end portion 18 thereof folded back upon the side wallalongv a transverse fold line 2l), the folded end portion 1u beingsecured through both thicknesses thereof only to the adjacent side wall14 of the body adjacent to the fold line 2d as by the heat seal 26extending transversely across the body, and the folded end portion 13remote from the fold line 2G beyond the heat seal 26 being free ofattachment to the adjacent side wall 14 and having both thicknesses ofthe free portion secured only to each other by a separate transverseheat seal 27.

rom the foregoing detailed description, it is believed apparent that thepresent invention contemplates the provision of a bag-like receptaclehaving an improved strong, durable and leak-proof bottom structureadapted to be produced in accordance with a novel and improvedproduction method. The bags produced by the method possess full capacityand the bottom is effectively sealed transversely thereacross by meansof the heat seal 26 which firmly unites both thicknesses of the foldedbottom portion 1fand one adjacent side wail 141 to thereby give fullcapacity to the bag, and the additional heat seal 27 firmly unites thefree end of the portion 18 through both thicknesses of the materialentirely independent of both of the bag walls to thereby give addedassurance as to the leak-proof and sift-proof qualities of the bag. Bymeans of the improved method, the heat and pressure required to form thebottom seal is considerably reduced because of the fact that a minimumnumber of thicknesses of material are operated upon thus obviouslyreducing the amount of heat required to effectively seal the desiredareas. Furthermore, the improved method may be carried out in acontinuous manner and is readily adapted for commercial production ofthe improved bag units. The method enables quantity production of bagsfrom all types of heat scalable materials even though certain of thesematerials may have a very critical range within which heat may be safelyapplied, and it is likewise effective in the production of commoditybags from materials which are not necessarily extremely critical orsensitive to high sealing heats.

It should be understood that it is not desired or intended to limit thisinvention to the exact steps of the production method or to the precisedetails of construction of the bags herein shown and described, sincevarious modifications within the scope of the appended claims may occurto persons skilled in the art to which this invention pertains.

I claim:

1. The method of producing commodity bags, which comprises, forming aflat tubular body from a sheet of heat scalable material, transverselyfolding an end of the body back upon one of its side walls, sealing thefolded portion adjacent to the fold line through both thicknessesthereof to the adjacent body side wall by application of heat andpressure, and securing both thicknesses of the free end of the foldedportion beyond the seal to each other by application of heat andpressure only to the free end of the folded portion.

2, The method of producing commodity bags, which comprises, initiallyforming a flat tubular body from a sheet of heat scalable material,transversely folding an end of the body back upon one of its side walls,sealing the folded portion adjacent to the fold line through boththicknesses thereof to the adjacent body side wall by application ofheat and pressure, and securing both thicknesses of the free end of thefolded portion beyond the seal to each other by application of heat andpressure to the free end of the folded portion while providing means forpreventing the applied heat from being transmitted to the adjacent bodyside wall.

3. The method of producing commodity bags, which comprises, initiallyforming a dat tubular body from a sheet of heat scalable material,transversely folding an end of the body back upon one of its side walls,sealing the folded portion adjacent to the fold line through boththicknesses thereof to the adjacent body side wall by application ofheat and pressure, while providing means for preventing the applied heatfrom being transmitted to the other body side wall, and securing boththicknesses of the free end of the folded portion beyond the seal toeach other by application of heat and pressure to the free end of thefolded portion while providing means for preventing the applied heatfrom being transmitted to the adjacent body side wall.

4. The method of producing commodity bags, which comprises, initiallyforming a flat tubular body from a sheet of heat scalable material,transversely folding an end of the body back upon one of its side walls,internally separating the body side walls adjacent to the folded end,applying heat and pressure to the folded portion adjacent to the foldline through both thicknesses of the folded portion and the adjacentbody side wall to thereby secure both thicknesses of the folded portionto each other and to the adjacent side wall only, separating the freeend of the folded portion beyond the seal from the adjacent body sidewall, and applying heat and pressure to the free end of the foldedportion to thereby secure both thicknesses thereof only to each other.

5. The method of producing commodity bags, which comprises, initiallyforming a llat tubular body from a sheet of heat scalable material,folding an end portion of the body back upon one of its side walls alonga transverse fold line, internally separating the body side wallsadjacent to the fold line while separating the folded portion remotefrom the fold line from the adjacent body side Wall, applying heat andpressure to the folded portion adjacent to the fold line to therebysecure both thicknesses of the folded portion to each other and to theadjacent side Wall only while also applying heat and pressure to thefolded portion remote from the fold line to thereby secure boththicknesses thereof only to each other.

6. A commodity bag comprising, a at tubular body having an end portionthereof folded back upon itself to close the end of the body, saidfolded end closure portion being secured to the adjacent side wall ofsaidy body by a heat seal extending transversely thereacross, and saidfolded end closure portion beyond said heat seal being free ofattachment to the adjacent side wall with both thicknesses of said freeportion being secured to each other, the opposed side walls of said bodybeing free of attachment.

7. A commodity bag comprising, a flat tubular body having an end portionthereof folded back upon itself, said folded end portion being securedonly to the adjacent side wall of said body by a heat seal extendingtransversely thereacross, and said folded end portion beyond said heatseal being free of attachment to the adjacent side wall with boththicknesses of said free portion being secured only to each other.

8. A commodity bag comprising, a fiat tubular body having an end portionthereof folded back upon itself along a transverse fold line, saidfolded end portion adjacent to said fold line being secured only to theadjacent side wall of said body by a heat seal extending transverselythereacross, and said folded end portion remote from said fold line andbeyond said heat seal being free of attachment to the adjacent side wallwith both thicknesses of said free portion being secured only to eachother.

9. A commodity bag comprising, a flat tubular body having an end portionthereof folded back upon itself along a transverse fold line, saidfolded end portion adjacent to said fold line being secured through boththicknesses thereof only to the adjacent side wall of said body by aheat seal extending transversely thereacross, and said folded endportion remote from said fold line and beyond said heat seal being freeof attachment to the adjacent side wall with both thicknesses of saidfree portion being secured only to each other by a separate heat seal.

References Cited in the le of this patent UNITED STATES PATENTS

